NTSB has released the
final report on the tragic accident that killed a great pilot and
aircraft builder, Jim Wright. Last seen at Oshkosh 2003, Wright and his
lavishly recrafted Hughes H-1 Racer went down in
Wyoming, forced down by mechanical difficulties just
hours after leaving the annual event.
Herewith, the NTSB's final report...
NTSB: HISTORY OF FLIGHT
On August 4, 2003, at approximately 1835 mountain daylight time,
a Wright, Hughes 1-B amateur-built airplane, N258Y, was destroyed
following an uncontrolled descent to the terrain in Yellowstone
National Park, Wyoming. The private pilot, the sole occupant in the
airplane, was fatally injured. The flight was being conducted under
Title 14 CFR Part 91. Visual meteorological conditions prevailed
for the cross-country flight that originated at approximately 1735
from Gillette, Wyoming. The pilot had not filed a flight plan;
however, friends of the pilot said the destination was Cottage
Grove, Oregon [260 degrees for 758 nautical miles].
The pilot was flying from Oshkosh, Wisconsin, (Experimental
Aircraft Association fly-in) back to his home. Witnesses at
Gillette, Wyoming, said that he landed there for fuel at
approximately 1600. They said that he departed at approximately
1640, but returned and landed because his controllable propeller
was stuck in the high RPM position [takeoff position]. Several
witnesses said the pilot got on a ladder with some tools and
lubricant, and he worked in the vicinity of the propeller for some
time. They reported that he departed a second time at approximately
1735.
The pilot's lead
mechanic said that the pilot called him following his quick return
to Gillette, Wyoming. The pilot reported that he had had some
difficultly with the propeller remaining in high RPM (takeoff
position) after his first takeoff [this was a recurring problem].
The pilot said that he would lubricate it and adjust it, and if all
worked well, would continue his flight.
Several witnesses at Yellowstone National Park's Midway Geyser
basin area reported seeing the airplane approaching them at a "low
altitude" from the southeast. One witness said she "stopped to
watch the plane overhead because we heard the plane's engine
sounding 'rough,' The engine seemed to cut out with a little bit of
intermittent engine sound. Then it was quiet. The plane seemed to
be going very slowly....like as slow as it could go. Then
rocking....wings tipped back and forth. It looked like it was doing
aerobatics. It started going down and we kept waiting for it to
pull out. I remember it went straight down. My husband remembers a
large corkscrew." Another witness said "I witnessed a plane at
approximately 500 feet in a steep dive. It made about one-half
revolution before impacting the ground."
Another witness said "my wife and I heard a loud sputtering
noise which sounded like a noisy motor cycle. The noise ended with
a few loud pops and then was quiet. About 20? seconds later, I saw
a plane heading straight down, flipping around, out of control. As
it headed toward the ground, I thought the pilot seemed to regain
some control and started to pull out of the dive. Maybe? I heard
engine sounds again." Another witness said he "heard the sound of
an aircraft engine stalling. We looked to the east and saw an older
single engine plane gliding in a westward direction. The plane
appeared to be gliding and losing altitude."
One witness said he heard the airplane overhead and then it "cut
out"; he then "heard the engine go again." Another witness said
"the plane was about 100 feet in [the] air when I saw it. It was in
a vertical downward spiral. Right before it hit I heard the engine
over-revving, like the person was trying to pull the plane through
so he could save it." Yet another witness said "when I saw the
plane first, it was spiraling downward. I watched it and at the
very last second, it sounded as if the plane was revving up as if
to try and pull out."
PERSONAL INFORMATION
The pilot's most recent Federal Aviation Administration (FAA)
flight medical exam (third class) was on June 17, 2002, and at that
time he reported on his application that he had 2,500 hours of
flight experience. The pilot owned two other aircraft, a Beech
Bonanza and a Glasair III. The pilot's flight logbook was never
located.
AIRCRAFT INFORMATION
The airplane was a non-pressurized, single engine,
propeller-driven, single seat amateur-built replica of Howard
Hughes' 1-B racer. It was built in June 2002. Its estimated maximum
gross weight was 7,250 pounds. The original Hughes 1-B racer was
built in 1935, and is located in the Smithsonian Aviation Museum in
Washington D.C. The airplane was powered by a Pratt and Whitney
R-1535-11, fourteen cylinder (two banks of seven cylinders), round,
reciprocating, air cooled, normally aspirated (carbureted),
super-charged (RPM ratio was 8.7 to 1) engine which had a maximum
takeoff rating of 750 horsepower at sea level. The last condition
inspection was performed in June 2003. The lead mechanic estimated
that the airplane had approximately 74 hours of flight at the time
of the accident.
The lead mechanic said that the airplane was "very
aerodynamically clean" and could glide a long ways. The airplane
"would take a long time to slow down." He said that there was no
twist in the wing, and the wing was tapered. The resultant design
permitted the wing tip and its associated aileron to stall before
the wing root. The stall speeds were 80-82 knots with full flaps,
and 90-92 knots clean. The airplane would cruise at 280 to 300
knots at 30% power; fuel consumption was 32-35 gallons per hour
(gph). Normal takeoff fuel consumption was approximately 75 gph;
maximum power fuel consumption was approximately 96 gph.
The propeller was a
modified constant speed Hamilton Standard 12D40 hub, which was
controlled by a governor using oil pressure and opposing counter
weights. The blades were from an Italian T-28, and were highly
modified for high speed. The counter weight brackets had been
changed from 15 degrees to 20 degrees to allow the propeller to
generate more thrust at a lower RPM. The aerodynamic twisting
forces of the blade could over power the centrifugal forces of the
counter weight if the hub was not consistently lubricated.
Consequently, particularly under high density altitude situations,
the propeller pitch would intermittently stick in the fine pitch
position. The lead mechanic said that a little lubrication of the
shaft, and a small adjustment to the counter weights would take
care of the problem. He also reported that although the 20 degree
counterweight brackets were installed, they were adjusted to limit
the blade travel to 16 degrees.
The airplane was constructed with four rubber bladder-type fuel
cells and two metal tanks for a total capacity of 304 gallons of
fuel. There were four tanks in the wings; the two outboard fuel
tanks (metal) held 14 gallons each and the two inboard fuel tanks
held 67 gallons each. The aft main body tank held 102 gallons of
fuel and the forward body tank held 40 gallons. The forward body
tank was used for takeoff, landing, and emergency situations,
because it had the highest head pressure with high angles of attack
during takeoff and landing. Additionally, keeping fuel in the
forward body tank kept the airplane within center of gravity
limitations, i.e., if the forward body tank was used up before any
wing tank fuel was used, the airplane's center of gravity would be
aft of limits.
The pilot was wearing a parachute at the time of the accident.
He had told his lead mechanic and several friends that if
"something goes wrong, I'm bailing out." The airplane was equipped
with a moving map Global Positioning System.
METEOROLOGICAL INFORMATION
At 1746, the weather conditions at West Yellowstone Airport
(elevation 6,644 feet), West Yellowstone, Montana, 320 degrees, 18
nautical miles (nm) from the accident site, were as follows: wind
160 degrees at 8 knots; visibility 20 statute miles; cloud
condition 4,000 feet broken; temperature 72 degrees Fahrenheit; dew
point 48 degrees Fahrenheit; altimeter setting 30.26. The density
altitude at the accident site was calculated to be 9,477 feet.
WRECKAGE AND IMPACT INFORMATION
The airplane was found
in Yellowstone National Park's Midway Geyser Basin (N44 degrees,
31', 33.8"; W110 degrees, 49', 54.5"; elevation 7,255 feet). The
initial impact was on friable, geyser mineral deposits, on the west
side of the Firehole River; the initial impact location was
approximately 35 feet above the river. The airplane's engine and
right wing (inboard half) came to rest, in the river, near the east
bank, approximately 125 feet northeast of the initial impact point.
The main fuselage and separated empennage were located
approximately 75 feet north of the engine, on the east bank of the
river. The right elevator was found approximately 70 feet east of
the empennage, on the highway which was paralleling the river.
Numerous fragments of metal and wood were found at the impact
point, in the river, along the bank of the river, and on the
highway. All of the airplane's major components were accounted for
at the accident site.
A photograph taken (by a nearby tourist) at the exact moment the
airplane impacted the terrain indicated that the airplane was
nearly vertical, with the longitudinal axis of the fuselage angled
approximately 40 degrees towards the right wing. Three cylinders
from the front row (approximately from 8 o'clock to 5 o'clock, from
the pilot's seat) were separated from the engine, and the three
adjacent cylinders in the second row were also separated. The
impeller blades from the engine's super charger exhibited uniform
damage to their leading edges and its housing exhibited distinct
impact marks with minimal smearing, which suggests low rotation
rate at the time of impact. Both propeller blades had stripped
their blade bushings, and one propeller blade was loose in the hub.
The second blade was bent aft, and conformed to the engine. The
propeller manufacturer's representative said that the "extent and
type of damage to the propeller blades suggest a low RPM at the
time of impact." Both blades exhibited minimal leading edge damage
and minimal chord wise striations. Neither of the two approximate 7
pound propeller blade counterweights (with caps and hardware) were
found at the accident site.
The landing gear was found in the up position. The fuel selector
was found in the forward body tank position.
MEDICAL AND PATHOLOGICAL INFORMATION
An autopsy was performed on the pilot by Yellowstone Pathology
Institute, Inc., Billings, Montana, for the Yellowstone National
Park, Wyoming, on August 6, 2003. The pathologist reported that no
anatomical or physiological conditions in the pilot, which might
have contributed to the accident, were identified.
The FAA's Civil Aeromedical Institute (CAMI) in Oklahoma City,
Oklahoma, performed toxicology tests on the pilot. According to
CAMI's report (#200300242001), tests on the blood and urine did not
detect any carbon monoxide, cyanide, nor ethanol. However,
sertraline was found in the blood and urine, as well as its
metabolite, desmethylsertraline. The NTSB medical officer said
sertraline, trade name Zoloft, is a prescription antidepressant
medication, which is also used for the treatment of
obsessive-compulsive disorder, panic disorder, post-traumatic
stress disorder, pre-menstrual dysphoric disorder, and social
anxiety disorder.
TESTS AND RESEARCH
Examination of the propeller's hub found that the two
counterweight brackets had separated from their counterweight
shafts in different manners. The #2 counterweight shaft was in
place with its respective washers and bearings. The #1
counterweight shaft was separated inside its hole, on an
approximate 45 degree angle, and the hole itself was distorted in
an oblong manner. Additionally, symmetrical impact marks were
identified on the aft face of the cylinder which matched the
separated ends of the counterweight brackets.
Examination of the #2 counterweight bracket revealed a fatigue
crack at the proximal end of the counterweight slot which extended
over approximately 70% of the inner arm. Approximately 60% of the
fatigue crack exhibited oxidation, and was heavily damaged by
fracture face recontact [hammering]. The NTSB
Investigator-In-Charge asked Hamilton Sundstrand to look at these
parts from the airplane's modified Hamilton Standard 12D40
propeller assembly. They examined the identified fatigue crack on
the #2 counterweight bracket and the fractured #1 counterweight
bracket. Their representative said that the fatigue crack and
associated over load failures provided insufficient physical
evidence to conclude whether the #2 counterweight bracket failed
prior to or at impact. A metallurgist from the NTSB reviewed
Hamilton Sundstrand's report and performed an examination of the
propeller components. Based on the fractographic evidence, the NTSB
metallurgist could not rule out the possibility that the #2
counterweight bracket failed due to the fatigue prior to
impact.
The propeller's cylinder was found crushed on one side, locking
the piston inside the cylinder. Measurements of the piston's
position indicated that the cylinder was extended 1.25 inches. The
zero extension position of the cylinder was high blade angle (44
degrees), or cruise position. The full extension position of the
cylinder was 2.75 inches, which was the low blade angle (24
degrees), or takeoff position. This indicated that the cylinder was
found at 54.5% of full travel, corresponding to a blade angle of
34.9 degrees.
The lead mechanic said that if a propeller counterweight were to
separate in flight, aerodynamic forces would drive the blade
towards fine pitch or low blade angle. The blade's rotation would
be limited to the low blade angle, of 24 degrees, by the remaining
portion of its counterweight bracket arm which would contact and be
stopped by the propeller's barrel.
Additional impact
signatures were identified on the propeller's shim plates. Hamilton
Sundstrand examined the shim plates, and determined that there was
an angular difference between the two blades, at the time of
impact, of approximately 10 degrees. The lead mechanic said that
one blade was at the low blade angle of 24 degrees, the measured
angular difference of 10 degrees, would indicate that the other
blade was at an angle of 34 degrees. The agreement between this
derived blade angle of 34 degrees and the piston position of 34.9
degrees suggests that one blade was still slaved to it's
counterweight at the time of impact and one blade was not.
The NTSB IIC interviewed a highly experienced agricultural
pilot, who was familiar with this type of propeller assembly, and
is certificated as an Airframe and Power Plant (A&P) mechanic
and has FAA Inspection Authorization (IA), who said, "the loss of a
counterweight in flight would cause significant imbalance and
subsequent vibration to the aircraft. It is possible that the
magnitude of the vibration would be sufficient to create collateral
damage to the airplane's structure."
ADDITIONAL INFORMATION
The airplane, including all components and logbooks, was
released to the pilot's family on September 8, 2003.
The National Transportation Safety Board determines the
probable cause(s) of this accident as follows:
The in-flight loss of a propeller counterweight, followed by
the pilot's loss of aircraft control during a forced landing
attempt and subsequent inadvertent stall/spin to the
ground.